Handling Mixed-Criticality in SoC-based Real-Time Embedded Systems
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Handling Mixed-Criticality in SoC-based Real-Time Embedded Systems Rodolfo Pellizzoni, Patrick Meredith, Min-Young Nam, Mu Sun, Marco Caccamo, Lui Sha Presented by Rafael Olaechea 1
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Handling Mixed-Criticality in SoC-based Real-Time Embedded Systems. Rodolfo Pellizzoni , Patrick Meredith , Min - Young Nam, Mu Sun, Marco Caccamo , Lui Sha Presented by Rafael Olaechea. Platform Based Design for Safety Critical Systems. Platform-Based Design of Embedded Systems - PowerPoint PPT Presentation
Transcript of Handling Mixed-Criticality in SoC-based Real-Time Embedded Systems
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Handling Mixed-Criticality in SoC-based Real-Time Embedded Systems
Rodolfo Pellizzoni, Patrick Meredith, Min-Young Nam, Mu Sun, Marco Caccamo, Lui Sha
Presented by Rafael Olaechea
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Platform Based Design for Safety Critical Systems
• Platform-Based Design of Embedded Systems– Reuse of a set of libraries and components– Automatic Generation of implementation– Help perform model checking on generated
systems
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Platform Based Design for Safety Critical Systems
• Platform-Based Design of Embedded Systems– Reuse of a set of libraries and components– Automatic Generation of implementation– Help perform model checking on generated
systems• But Safety Critical Systems have special needs– Isolation of safety critical from non-safety critical
processes– Ensures isolation at runtime
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Architecture Description Language
• Specifies logical functionality and requirements– Processes • Computation (Period, Deadline, Execution)• Communication Requests (number of frames, and
deadline)
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Architecture Description Language
• Specifies logical functionality and requirements– Processes
• Computation (Period, Deadline, Execution)• Communication Requests (number of frames, and
deadline)
• Specifies Hardware Platform– Processor– Memory– Bus
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Enforcing Safety of low criticality tasks
• Based on AADL specified requirements– Functional Certificate• Runtime Monitoring of Events
– Example with Programmer and Pacer interface
– Timing Certificate• Ensuring Communication and computation bounds
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Pacemaker Platform
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Pacemaker Platform
Timing Constraints will be enforced by process scheduler
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Wrappers Enforcing Communication Safety
• Bus Safety– A timeslot is assigned to each process– Hardware wrapper prevents data being sent if
frame is not for the process
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Wrappers Enforcing Communication Safety
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Wrappers Enforcing Communication Safety
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Wrappers Enforcing Communication Safety
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Runtime Monitoring of tasks
Task (HW or CPU) Event Specification
Corrective Action or Disabling of Action
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Runtime Monitoring of tasks
Task (HW or CPU) Event Specification
Corrective Action or Disabling of Action
Specification Logic:
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Runtime Monitoring of tasks
Task (HW or CPU) Event Specification
Corrective Action or Disabling of Action
Specification Logic:Extended Regular ExpressionsPast Time Linear Temporal Logic
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Runtime Monitoring of tasks
Task (HW or CPU) Event Specification
Corrective Action or Disabling of Action
Specification Logic:Extended Regular ExpressionsPast Time Linear Temporal LogicSymbolic names for queues and read/writes
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Programmer Process updating heartbeat rate
Programmer process will update parameters based on RF module input
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Programmer Process updating heartbeat rate
Programmer process will update parameters based on RF module inputBut Pacer and Rate Adapter are more critical
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Programmer Process updating heartbeat rate parameters
Programmer process will update parameters based on RF module inputBut Pacer and Rate Adapter are more critical
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Programmer Process updating heartbeat rate parameters
Programmer Rate Adapter PacerParameter + Check
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Programmer Process updating heartbeat rate parameters
Programmer Rate Adapter PacerParameter + Check
Success
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Programmer Process updating heartbeat rate parameters
Programmer Rate Adapter PacerParameter + Check
Success
Parameter + Check
Success
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Programmer Process updating heartbeat rate parameters
Programmer Rate Adapter PacerParameter + Check
Success
Parameter + Check
Success
Commit
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Programmer Process updating heartbeat rate parameters
Programmer Rate Adapter PacerParameter + Check
Success
Parameter + Check
Success
CommitCommit
But Programmer could fail after one commit causing discomfort to patient
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Solution: Extract the commits logic into the certified monitors
• Events are specified in terms of values read/writes to/from symbolic queues
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Solution: Extract the commits logic into the certified monitors
• Monitor sends the commit commands once success are received
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Solution: Extract the commits logic into the certified monitors
• Prevent Programmer from sending commits or checks before receiving an answer
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Programmer Process updating heartbeat rate parameters
Programmer Rate Adapter PacerParameter + Check
Success
Parameter + Check
Success
Monitor
Commit
Commit
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Platform controlling Battery life
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Schedule Generation and Timing Isolation
• Communication Requests– Periodic task to be assigned to the communication
bus• Computation Requests– Periodic task to its processor
• Earliest Deadline Schedule Generated– Statically for hyper-period
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Schedule Generation and Timing Isolation
Rate Data and SignalBuffer write are part of the communication infrastructure processor
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Conclusions
• Helps combining low and high criticality tasks– Low Priority task safe behavior enforced• Timing• Logically
• Model tasks requirements on AADL– Computation– Communication– Generate Safe Schedules
![Self-Organized Criticality (SOC) · References: l[1] P. Bak, How Nature Works.Springer -Verlag, NY, 1986. l[2] H.J.Jensen.Self-Organized Criticality – Emergent Complex Behavior](https://static.fdocuments.us/doc/165x107/5d09279688c993db4a8b5727/self-organized-criticality-soc-references-l1-p-bak-how-nature-worksspringer.jpg)
